Dispensing pump assembly for bakery materials

ABSTRACT

The specification and drawings disclose a dispensing pump assembly which includes a first, vertically extending tubular cylinder for a piston mounted therein and adapted to reciprocate vertically. At the lower end of the cylinder, there is an inlet provided with a check valve which permits flow in only one direction into the cylinder. Immediately above the check valve is a discharge outlet having an outlet check valve. Preferably, the inlet and outlet check valves are relatively large diameter balls. Extending upwardly from the discharge check valve is a discharge pipe or tube which connects to a horizontally extending dispensing control assembly. The dispensing control assembly includes a pipe having an outlet and a reciprocal slide valve which controls flow through the outlet. Both the piston and the slide valve are controlled by separate double acting air cylinders. Additionally, control means are provided for controlling the operation of the air cylinders so that the valve is opened only when the piston is moving toward the inlet valve.

United States Patent [191 Marine et a1.

1541 DISPENSING PUMP ASSEMBLY FOR BAKERY MATERIALS [75] Inventors: Richard L. Morine, Mentor; James J. Hokes, Lakewood, both of Ohio [73] Assignee: Fedco, Inc., Mentor, Ohio [22] Filed: April 29, 1971 [21] Appl. No.: 138,475

52 U.S. c1 ..222/334 [51] Int. Cl ..G0lf 11/06 [58] Field of Search ..222/334, 383, 380, 504, 377, 222/385; 417/900; 137/565 [56] References Cited UNITED STATES PATENTS 3,125,257 3/1964 Vukich ..4l7/9OO X 2,606,696 8/1952 Miner ..222/334 Primary Examiner-Stanley H. Tollberg Attorney-Fay, Sharpe & Mulholland [45.1 Feb. 6, 1973 [5 7] ABSTRACT The specification and drawings disclose a dispensing pump assembly which includes a first, vertically extending tubular cylinder for a piston mounted therein and adapted to reciprocate vertically. At the lower end of the cylinder, there is an inlet provided with a check valve which permits flow in only one direction into the cylinder. Immediately above the check valve is a discharge outlet having an outlet check valve. Preferably, the inlet and outlet check valves are relatively large diameter balls. Extending upwardly from the discharge check valve is a discharge pipe or tube which connects to a horizontally extending dispensing control assembly. The dispensing control assembly includes a pipe having an outlet and a reciprocal slide valve which controls flow through the outlet. Both the piston and the slide valve are controlled by separate double acting air cylinders. Additionally, control means are provided for controlling the operation of the air cylinders so that the valve is opened only when the piston is moving toward the inlet valve.

4 Claims, 6 Drawing Figures DISPENSING PUMP ASSEMBLY FOR BAKERY MATERIALS The subject invention is directed to the dispensing art and, more particularly, to a dispensing pump assembly capable of discharging closely controlled quantities of fluid materials.

The pump is particularly suited for use in dispensing cake batters and the like, and will be described with particular reference thereto; however, it should be appreciated that it can be used for dispensing many different types of food products, chemicals or other fluid materials.

In the baking industry, there is a distinct need for a small dispensing pump assembly which is capable of dispensing closely controlled quantities of cake batters and similar fluids. The need for such a unit is especially prevalent among the small job type bakeries in which only a limited quantity of any one product is made at a time. The use of the large, commercially available manifold dispensing assemblies which dispense a multiple number of quantities simultaneously cannot be economically justified in the small bakery. Accordingly, manual filling techniques are typically used.

Although certain prior art units are commercially available, these generally utilize an overhead hopper which feeds to a small manifold assembly. In use, the batter must be transferred from the mixing bowls to the overhead hopper. This is relatively difficult since the mixing bowls may weigh several hundred pounds,

requiring the use of at least two men or hoisting equip-.

ment. Further, there can be substantial waste of batter because of the arrangements of the hoppers and manifolds. Additionally, the hopper and manifold arrangements are difficult to clean and relatively expensive.

Other types of dispensing pump units are available which use an oscillated valve to control both filling and discharging from a piston cylinder. Typically, the piston and cylinder are operated by air cylinders controlled by a single four-way valve. In operation, difficulties are encountered in assuring proper correlation in movement of the piston and valve. For example, variations in batter consistency can vary the valve opening and closing time.

In addition, the same hopper and cleaning problems are present as in the units discussed above.

The subject invention provides a highly simplified dispensing pump assembly which can be adjusted to dispense closely controlled quantities of many fluid materials. The assembly is arranged so that it can be used to pump directly from the mixing bowls to the pans. Further, if desired, the unit can be permanently mounted in a production line to draw from any type of hopper or container.

In accordance-with one aspect, the invention comprises a dispensing pump assembly which includes a first, vertically extending tubular cylinder for a piston mounted therein and adapted to reciprocate vertically. At the lower end of the cylinder, there is an inlet provided with a check valve which permits flow in only one direction into the cylinder. Immediately above the check valve is a discharge outlet having an outlet check valve. Preferably, the inlet and outlet check valves are relatively large diameter balls. Extending upwardly from the discharge check valve is a discharge pipe or tube which connects to a horizontally extending dispensing control assembly. The dispensing control assembly includes a pipe having an outlet and a recipro- 7 cal slide valve which controls flow through the outlet. Both the piston and the slide valve are controlled by separate double acting air cylinders. Additionally, control means are provided for controlling the operation of the air cylinders so that the valve is opened only when the piston is moving toward the inlet valve.

In accordance with a more limited aspect, the assembly is provided with means which permit the total length of piston reciprocation to be varied so that the quantity. of material discharged with each stroke of the piston can be adjusted.

The combination of the adjustable piston stroke and the slide valve outlet control allows closely controlled quantities to be dispensed. The air operated slide valve assures rapid cut-off following each cycle.

Accordingly, a primary object of the invention is the provision of a dispensing pump assembly which is simple in construction and operation.

Another object of the invention is the provision of a pump assembly of the type described which can handle a wide variety of fluid materials and which is easy to disassemble for cleaning and repairing.

Yet another object is the provision of an assembly which can dispense closely controlled quantities of materials in single or multiple cycles.

The above and other objects and advantages will become apparent from the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevational view showing the improved dispensing pump assembly releasably mounted on a mixing bowl of the type often used in bakeries;

FIG. 2 is a plan view taken on line 2-2 of FIG. 1;

FIG. 3 is a vertical cross-sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is a cross-sectional view taken on line 4-4 of FIG. 2;

FIG. 5 is a schematic showing of the air control circuits; and,

FIG. 6 is cross-sectional view showing a modified form of outlet for the unit.

Referring more particularly to FIG. 1, the preferred embodiment of the dispensing pump assembly 10 is shown releasably connected to a standard bakery mixing bowl 12 by a releasablemounting assembly 14. Bowl 12 is a standard bowl formed from stainless steel or the like and having a raised bottom wall 16 and a circumferential side wall 18 which terminates at its upper end in an outwardly extending flange portion 20. The pump assembly 10 is shown releasably connected to the upper flanged end by a support frame 22 comprising a pair of bracket portions 24 which extend laterally from a cross bar 25. At their outer ends, the brackets have slots 27 adapted to receive the flange 20. Extending from the opposite side of bar 25 is a band 26 which encircles the pump cylinder 40. A clamp bar 30 is positioned between bar 25 and the pump cylinder. A threaded shaft 32 passes through bar 25 and has its inner end rotatably received in clamp bar 30. A hand knob 33 allows shaft 32 to be tightened to clamp the pump against band 26.

As best shown in FIG. 2, the pump assembly is carried at a location such that its lower end is over the depressed side portion of the bottom wall of the mixing bowl 12.

The arrangement thus far described is not of substantial importance to the invention and many other types of mounting and support arrangements could be used, if desired. Additionally, it should be understood that although the arrangement shown in the preferred embodiment is adapted for use in conjunction with a mixing bowl, the assembly could be permanently installed on a bakery line and used to pump from many types of containers or supply hoppers.

Of importance to the invention is the general construction of the pump assembly itself and its overall method of actuation and control. The construction of the pump assembly 10 can best be understood by reference to FIGS. 3 and 4. The details could, of course, vary substantially from that shown in the drawings. However, as shown, the pump assembly comprises a main, vertically extending cylinder having an outlet branch 42 connected thereto at its lower end. The main cylinder 40 and the branch member 42 are, in the preferred embodiment, formed from stainless steel and each have a cylindrical configuration. Extending outwardly about the lower end of the main cylinder 40 is a short flange 44 which provides means for releasable connection of the foot valve assembly 46.

Foot valve assembly 46 is a one-way ball-type check valve including a plastic ball member 48. The ball 48 is carried for free vertical movement in a cage-like ar' rangement comprising a first horizontally extending pin member 50 which is joined to the sides of the lower end of main cylinder 40. The remaining portions of the cage are defined by three or more pins 52 which extend upwardly from the inlet defining flange member 54. Flange member 54 includes a laterally extending flange portion 58 and a central opening 56 through which the batter or other material is drawn during a pumping operation. Member 54 is releasably connected to the lower end of cylinder 40 by a conventional split clamp ring 60 which engages the upper surface of flange 44 and the lower surface of flange 58 to releasably clamp the member 54 to the lower end of cylinder 40. Preferably, a resilient seal or gasket member 62 is positioned between the opposing faces of flange 44 and flange 58.

The discharge valve assembly for the pump unit is carried at the upper end of the laterally extending branch 42 and is indicated generally by the reference numeral 64. The discharge check valve assembly 64 is a ball-type check valve similar to the inlet or foot valve assembly 46 and comprises a cylindrical plastic ball member 66 sized so as to seat closely with the shoulder 68 at the outlet end of branch 42. Three or more pin members 70 extend upwardly from the flange 72 and provide guide for vertical movement of the ball 66.

Connected to flange 72 by a split clamp ring 74 is a discharge tube 76 having an enlarged lower end portion 78 which is spaced outwardly from the ball 66. A horizontally extending pin member 80 is positioned between the side walls of the discharge pipe 76 and limits the upper movement of the ball 66. As can be appreciated, the arrangement thus far described allows flow in one direction inward through opening 56 and outwardly through the discharge pipe 76.

The pumping action of the assembly is achieved by a piston 82 reciprocated within the vertically extending cylinder 40. Piston 82 is preferably formed from plastic or other suitable material and is arranged to be closely received within the inner diameter of cylinder 40. Preferably, O-rings or the like 84 are carried within suitable grooves formed in the outer surface of piston 82 and serve to seal between the piston and the wall of the cylinder.

The piston 82 is reciprocated by a double acting air cylinder 84 carried at the upper end of the cylinder 40. It can be seen that a first rod 86 is releasably connected to the piston 82 in any convenient manner such as merely by threading it into the piston. The upper end of rod 86 is threadedly connected in a cylindrical guide block 88 which has its outer surface inwardly spaced from the inner surface of the tube 40. The piston rod 90 of the double acting air cylinder 84 is threadedly connected in the opposite side of guide block 88. Accordingly, actuation of the air cylinder 84' causes reciprocation of the piston 82.

In the embodiment under consideration, the air cylinder 84 and piston 82 are arranged so that they can be rapidly removed from the cylinder 40 for cleaning or the like. This can be accomplished by many different arrangements; however, in the subject embodiment, the air cylinder 84 is threadedly connected in a top plate member 92 which has a threaded center bore 94 which receives the threaded end 96 of cylinder 84. The top plate 92 is releasably connected to the laterally extending flange 98 by a split clamp ring 100 which engages the top surface of top plate 92 and the under surface of flange 98. Additionally, a gasket or seal member 102 is positioned between the opposed faces of the flange 98 and the top plate 92. As can be appreciated, merely by releasing the clamp ring 100, the entire piston and air cylinder assembly can be removed from the cylinder 40. Additionally, both the intake valve assembly 46 and the discharge assembly 64 can be removed in a similar manner to provide for easy cleaning of the entire unit.

Referring again to FIGS. 1 and 4, it will be seen that a discharge control assembly is connected to the upper end of discharge pipe 76. In the embodiment under consideration, the discharge control assembly 110 is formed integrally with the pump unit 10; however, for reasons which will hereafter be discussed, it is preferable at times that the assembly be releasably connected to the discharge pipe 76 such as through the use of a flexible hose.

Carried within the pipe 114 of the discharge assembly 110 is a cylindrical, slide valve member 116 which is preferably formed from a plastic such as polyethylene or the like. The valve member 116 is arranged to be reciprocated from the dotted line position 116 to the solid line position 116. In position 116', the valve closes off the discharge outlet port 118. This arrangement assures sharp cut-off of the material being dispensed.

The means for reciprocating the valve member 116 in timed relationship with the actuation of the pump comprises a double acting air cylinder 120 which has its piston rod 122 connected with the valve 116. It will be noted that the outer end of piston rod 122 is connected to a bar member 124 which extends across the interior of valve member 116. The ends of the member 122 are pinned or otherwise pivotally connected to valve member 116. This allows the valve assembly to be selfaligning in the pipe 114 and makes it easier to withdraw for cleaning. Additionally, the pivotal connection as sures the proper mating relationship between the valve and the interior wall of pipe 114.

In order to permit the piston and cylinder assembly to be removed from 114, the piston is connected to an end plate 124 which is releasably clamped to the end flange 126 by a split clamp ring member 128. Additionally, a seal or gasket 130 is preferably positioned between the opposed faces of the end plate 124 and the flange 126 to provide a fluid tight seal.

As can be appreciated, the operation of the pump actuating cylinder 84 and the valve actuating cylinder 120 must be closely controlled so that the valve is preferably open during a power stroke of the piston 82. Additionally, in order that closely metered amounts of material can be dispensed from the outlet port 1 18, the stroke of the pump piston must be adjustable. For this reason, a control circuit, as best shown in FIG. 5, is preferably used with the unit. Before describing the control circuit in detail, reference is made to FIG. 3 which shows the various control valves and their structural relationship with the unit. Note that a first pair of one-way air valves 136 and 138 is carried on an arcuate bracket 140. Bracket 140 is carried on a vertically extending rod 142 which is adjustably connected to the guide block 88. Note that the lower end of the rod 142 extends through a vertical opening formed in guide block 88 and is clamped therein by nuts 144 and 146. This allows the guide block 140 to be adjusted slightly so that the actuating portions 136 a and 138a of valves 136 and 138 can be closely adjusted so that on the lower end of the pump stroke, the actuating portions will engage the top surface of plate 92 to cause the valves to operate at the proper time during a pump stroke.

The upper limit of the pump stroke is arranged to be controlled by an air valve 150 carried on a bracket 152. Bracket 152 is mounted for vertical adjustment on a rod 154 which extends upwardly from the top plate 92. Note that the rod 154 extends through an opening in bracket 152 and a nut and hand knob 156. By releasing the hand knob 156, the position of the bar 152 and valve 150 can be vertically adjusted. Note that upon an upward stroke of the pump, the valve actuator 150a of valve 150 is engaged by the top surface of block 140 to cause actuation of the valve 150. By adjusting the position of valve 150, the total length of the stroke of the piston can be varied. The total lower limit of the stroke is, of course, generally fixed and extends to the dotted line position 82'.

Also carried with the air cylinder 84 is a pair of four- I way valves 160 and 162 which are interconnected with the two air cylinders 120 and 84 in a manner subsequently to be described with reference to FIG. 5.

CONTROL OPERATION The overall operation and functioning of the dispensing pump system can best be understood by reference to FIG. 5 which is a diagrammatic or schematic showing of the air control circuitry for the assembly. FIG. 5 shows the components of the system at the end of a suction stroke. That is, the piston 82 is at its upper limit of movement and the valve 116 is in a closed position with the cylinder fully extended. To initiate operation of a pump and discharge stroke, the pilot valve 190 is actuated permitting or causing the right side of the four-way valve 160 to be exhausted through line 192. The pilot valve 190 can be associated with any type of foot or hand operator or the like. Further, it should be understood that it could be electrically operated in response to an impulse received from a pan sensing means such as a proximity switch, electric eye or the like.

Upon shifting of the four-way valve 160 to the right, air flow from the air supply 194 is conducted through lines 196 and 198 to the upper end of the cylinder 84 actuating the piston downwardly and causing the pumping piston 82 to expel the batter or the like through the discharge check valve 84. As the air cylinder 84 moves downwardly, the bracket (see FIG. 3) disengages the actuator a of pilot valve 150. This shifts the pilot valve to a position wherein line 200 is connected to atmosphere relieving the pressure in the right-hand end of the four-way valve 162. This causes the fourway valve 162 to shift to the right and allows air to be conducted from air supply 194 to the left-hand end of cylinder 120 via lines 202 and 204. The operation of valve 150 similarly exhaust the pressure on the left-hand end of valve 160. However, this merely equalizes the pressures on both sides of pilot valve and the valve does not move from the position it was in.

Movement of the piston in cylinder 120 to the right opens the discharge valve 116 to permit the material to be discharged through outlet opening 118. In addition, as can be appreciated, the opening of valve 116 takes place substantially simultaneously with the pump stroke of piston 82. At the lower end of the pump stroke, the actuators 136a and 138a of pilot valves 136 and 138, respectively, are engaged with the cover plate 92 causing pilot valve 136 to move to a closed position and valve 138 to move to an opened position. Closure of valve 136 blocks discharge of air from the right side of pilot valve 160 thereby causing a pressure buildup and shifting of the pilot valve to the left to the solid line position shown. This reverses the flow of air to the cylinder 84 and air supplied from the source through line 196 and line 206 causing the piston 82 to be pulled upwardly for a suction stroke on the pump.

At the bottom of the pump stroke, the valve 138 is in an exhaust position. This has no effect upon the posi tion of the pilot valve 162 since valve 150 is also in an exhaust position and both sides of the valve 162 are under the same pressure. The pressure in the left-hand side of valve 162 builds up against the valve but has no effect on its position since the pressure on the right side is still reduced or in the exhaust position. HOwever, at the end of the up-stroke of the pump piston, valve 150 is actuated to its closed position causing pressure buildup within the right side of the four-way pilot valve 162. This shifts the pilot valve to the left to the position shown supplying air pressures to the right-hand end of cylinder 120 and moving the valve 116 to a closed position. Shortly prior to this time, the valve will have been released and consequently, the pressure is balanced on both sides of each of the four-way valves and the elements are maintained in the solid line position. However, if the pilot valve 190 is maintained in the down position, the pump will continually re-cycle until valve 190 is released.

Many different types of control arrangements could obviously be used. Additionally, mechanical interlocks or interconnections between the actuating piston and the discharge valve 116 could be provided, if desired. Additionally, it should be noted that the total upper length of stroke can be adjusted merely by adjusting the position of the pilot valve 150. For this reason, the valve 150 is shown (see FlG. 3) mounted on the adjustable arm 152 so that the point at which it is engaged and moved to a closed position can be varied as desired.

Also, it should be pointed out that the speed of piston movement can be controlled by limiting the rate of air bleed through valves 160 and 162. Note that an orifice is placed in lines 161 and 163. This allows adjustment for different fluids to control pump speed.

FIG. 6 shows how the dispensing control assembly can be modified to permit several separate streams to be dispensed simultaneously. This type of dispensing outlet arrangement is particularly useful when the assembly is being used for filling cupcake pans or the like. As shown, the modified assembly comprises a sleeve assembly 210 which is adapted to be closely received on the outer end of tube 114. A threaded stud 212 extends outwardly from the end of pipe 114 and passes through an opening sleeve 210. A wing nut 214 allows the sleeve 210 to be releasably held in position on pipe 114. The end of the sleeve 210 is sealed by an O-ring 216 which is clamped by the end of the sleeve against a collar 218. Collar 218 can be permanently connected to pipe 114 or releasably attached to a set screw or the like.

Extending downwardly from sleeve 210 area plurality of outlet tubes 119 through 122 having their lower ends located at any desired spacing. The upper ends of the tubes 119 through 122 pass through sleeve 210 at a spacing such that they are aligned with outlet 118. This arrangement allows the unit to be rapidly converted from single to multiple outlet use.

The invention has been described in great detail sufficient to enable one of ordinary skill in the dispensing art to make and use the same. Obviously, modifications and alterations of the preferred embodiment will occur to others upon a reading and understanding of the specification and it is out intention to include all such modifications and alterations as part of our invention insofar as they come within the scope of the appended claims.

What is claimed is:

1. A dispensing pump assembly comprising:

a first, vertically extending tubular cylinder having a piston carried therein and adapted to reciprocate vertically;

an inlet opening carried on the lower end of said first cylinder with an inlet check valve mounted in said opening and arranged to permit flow only in a direction into said first cylinder;

an outlet opening in the side wall of said first cylinder at a location below said piston and immediately above said inlet opening, an outlet check valve associated with said outlet opening and arranged to permit flow only in a direction out of said first cylinder;

a discharge pipe connected to said outlet opening and extending upwardly therefrom;

a discharge outlet in said discharge pipe and a discharge valve adapted to control flow through said through said discharge outlet, said discharge valve comprising a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe;

a first double acting air cylinder for reciprocating said piston and a second double acting air cylinder for operating said discharge valve;

operating means extending from said second double acting air cylinder axially through said discharge pipe to said valve;

control means for controlling the operation of said first and second double acting air cylinders, said control means including means for causing said discharge valve to be opened only when said piston is moving toward said inlet valve and,

wherein said reciprocal valve comprises a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe; and,

said second air cylinder being connected to said discharge pipe.

2. The dispensing pump assembly of claim 1 including adjustable stroke limiting means provided to vary the total length of reciprocation of said piston.

3. The dispensing pump assembly as defined in claim 2 wherein said adjustable stroke limiting means include a valve means which controls flow of air to said first double acting air cylinder.

4. A dispensing pump assembly comprising:

a first, vertically extending tubular cylinder having a piston carried therein and adapted to reciprocate vertically;

an inlet opening carried on the lower end of said first cylinder with an inlet check valve mounted in said opening and arranged to permit flow only in a direction into said first cylinder;

an outlet opening in the side wall of said first cylinder at a location below said piston and immediately above said inlet opening, an outlet check valve associated with said outlet opening and arranged to permit flow only in a direction out of said first cylinder;

a discharge pipe connected to said outlet opening and extending upwardly therefrom;

a discharge outlet in said discharge pipe and a discharge valve adapted to control flow through said discharge outlet, said discharge valve comprising a hollow, cylindrical, open-ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe;

a first double action air cylinder for reciprocating said piston and a second double acting air cylinder for operating said discharge valve;

operating means extending from said second double acting air cylinder axially through said discharge pipe to said valve; and,

control means for controlling the operation of said first and second double acting air cylinders, said control means including means for causing said discharge valve to be opened only when said piston is moving toward said inlet valve. 

1. A dispensing pump assembly comprising: a first, vertically extending tubular cylinder having a piston carried therein and adapted to reciprocate vertically; an inlet opening carried on the lower end of said first cylinder with an inlet check valve mounted in said opening and arranged to permit flow only in a direction into said first cylinder; an outlet opening in the side wall of said first cylinder at a location below said piston and immediately above said inlet opening, an outlet check valve associated with said outlet opening and arranged to permit flow only in a direction out of said first cylinder; a discharge pipe connected to said outlet opening and extending upwardly therefrom; a discharge outlet in said discharge pipe and a discharge valve adapted to control flow through said through said discharge outlet, said discharge valve comprising a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe; a first double acting air cylinder for reciprocating said piston and a second double acting air cylinder for operating said discharge valve; operating means extending from said second double acting air cylinder axially through said discharge pipe to said valve; control means for controlling the operation of said first and second double acting air cylinders, said control means including means for causing said discharge valve to be opened only when said piston is moving toward said inlet valve and, wherein said reciprocal valve comprises a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe; and, said second air cylinder being connected to said discharge pipe.
 1. A dispensing pump assembly comprising: a first, vertically extending tubular cylinder having a piston carried therein and adapted to reciprocate vertically; an inlet opening carried on the lower end of said first cylinder with an inlet check valve mounted in said opening and arranged to permit flow only in a direction into said first cylinder; an outlet opening in the side wall of said first cylinder at a location below said piston and immediately above said inlet opening, an outlet check valve associated with said outlet opening and arranged to permit flow only in a direction out of said first cylinder; a discharge pipe connected to said outlet opening and extending upwardly therefrom; a discharge outlet in said discharge pipe and a discharge valve adapted to control flow through said through said discharge outlet, said discharge valve comprising a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe; a first double acting air cylinder for reciprocating said piston and a second double acting air cylinder for operating said discharge valve; operating means extending from said second double acting air cylinder axially through said discharge pipe to said valve; control means for controlling the operation of said first and second double acting air cylinders, said control means including means for causing said discharge valve to be opened only when said piston is moving toward said inlet valve and, wherein said reciprocal valve comprises a hollow, cylindrical, open ended member positioned in said discharge pipe, said hollow member having an outer diameter adapted to be closely received in said discharge pipe; and, said second air cylinder being connected to said discharge pipe.
 2. The dispensing pump assembly of claim 1 including adjustable stroke limiting means provided to vary the total length of reciprocation of said piston.
 3. The dispensing pump assembly as defined in claim 2 wherein said adjustable stroke limiting means include a valve means which controls flow of air to said first double acting air cylinder. 